Frequency conversion system



Jul .18, 1939. Az m Re. 21',l53

' FRE UENCY CONVERSION SYSTEM Original Filed Jan. 31, 1936 4 Sheets-she t '1 qt f FILTER OOOOOEkLk FIG.3.

FIGJ.

FIGQ5.

FIG.6.

INVENTOR- LO IS A. HAZELTINE,

ATTORNEY.

July 18, 1939. A-. HAZZELTINE Re.

FREQUENCY CONVERSION SYSTEM 4 Sheets-Sheet '2 Original Filed Jan. 51; 1936 FIG. 8.

FILTER FIGJO.

i ni'f FIGJZ.

flif2 FIG l4 v FlG.9.

' INVENTOR. LOUIS A. HAZELTINE ATTORNEY.

July 18, 1939. L. A. HAZELTINE 3 FREQUENCY CONVERSION SYSTEH Original Filed Jan. 31, 1936 4 Sheets-Sheet 3 o o no 0 o o o o a a o a u n o 0 INVENTOR.

, LOUIS A. HAZEL NE,

ATTORNEY.

- 755 the combined characteristic curveof the tube Reissued July s, 1939 PATENT OFFICE.

FREQUENCY CONVERSION SYSTEM Louis A. Hazeltine, Hoboken, N. .flf asslgnor to Haneitine Corporation, a corporation of Delaware Original No. 2,113,464, dated April 5, 1938, Serial 7 No. 61,819, January 31, 1936. Application for reissue June 4, 1938, Serial No. 2i1,818

'17 Claims.

v two alternating voltages of given frequencies on a single thermionic vacuum tube, or on a pair of such tubes connected in balanced relation,

thereby to obtain variations in the electron emission which, due to the non-linear characteristics of .such tubes, contains components having frequencies. respectively equal to the sum and difference of the given frequencies.

' It is well known that the electron emission current in a thermionic tube is substantially proportional to thethree-halves power of the effective combined voltage ,which controls it, when this voltage is in one direction, and is zero when ,6 this combined voltage is in the other direction. Thistype of non-linear characteristic, relating emission current with voltage, inherently introduces distortioninto the output of the frequency converter, which distortion is often objectionable.v

Two general expedients have been resorted to in practice to eliminate the type of distortion noted above. The first, which is applicable when small impressed voltages are to be used, com- "prises limiting the voltage variations to such a a narrow range on the characteristic curve of the tube" that the portion of this curve utilized approximates a parabolic arc, whereby the emission current contains no considerable terms beyond the square-law term. This square-law term has three parts, proportional, respectively, to the s qfiare of each voltage and to theproduct of the two voltages, the last of which contains the desired components having the sum'frequency and the difference frequency. -It willthus be seen that by employing this expedient distortion issubstantially eliminated, provided that the coinponents representing thesquare of each voltage can be filtered out, which is not always feasible.

The second expedient, which is suitable when large impressed voltages are to be used, comprises, 1

50 employing in the anode circuit of the control tube ayresistance which is high as cempared to the internal anode resistance of the tube above the anode current cut-off-point, and in .ope'rat ing the tube through thk cut-oii point, so that and the external resistance consists of a portion corresponding to zero current which is linear alone, and a portion depending primarily on the external resistance, which is also approximately linear when considered alone.

Some of the distortion components in the output of a frequency converter of the general type described above are eliminated when two thermionic tubes are used in 'balancedrelation. In place. of two such tubes, it'has been proposed to use for frequency .conversign a thermionic vacuum tube having a pair of anodes, a pair of control electrodes, and a single cathode. Such a system is shown and described in United States Patent No. 1,343,306, to Carson, granted June 15, 1920. Tubes of this construction have not been used extensively in theabove-referred-to application because, among other factors, their arrangement has been such that .a relatively large variation in the control voltage applied between' the control electrodes is required to produce the desired variation in the division of the current between theanodes, with the result that a single tube of this type is inferior in operation to two separate three-electrode tubes. Further, their, arrangement does not entirely eliminate the distortion in the output because the variation inthe division of current between the anodes is not directly proportional to the potential diiference applied between the control electrodes. 30 ,In mycopending application Serial No. 61,820, filed January 31, 1936,-there is disclosed animproved two-anode electron discharge device of novel construction and arrangement which op-. erates in a new manner, such that the desired variation in the division of the current between the two anodes may be effected by relatively small variations in'th'e controlling influence and i is substantially proportional to the control. Briefly described, this improved electron dis"- charge device comprises a cathode; a pair of anodes positioned closely adjacent to eachother, and control means, the elements being so ar-' ranged that the electrons emitted by the cathode to the anodes are effectively divided into a plu rality of parallel streams which are deflected periodically and alternately from each of the two anodes toward the other in accordance with vari- 'ations in a periodic control, whereby the desired variations in the division of the current between the two anodes are obtained. with such an arrangement of the tube elements, a relatively 1 small change in the control is suffi'cient largely to deflect the electron streams from one an'ode\ to the other, thereby to produce the desired vari- 55 trol electrodes.

ture, the total electron emissionto the anodes ations in the division 0! the current between the two anodes. Due to the close spacing between the anodes the change in direction or the electron streams is so small that the division of electrons between the two anodes is substantially proportional to the controlling influence, up to the point at which the electron streams are completely deflected from one anode to the other.

Various arrangements of the tube elements may be employed to obtain the operation described above. One form of tube structure includes a pair of control electrodes in the form of interleaved helices, coaxially disposed about the cath- -ode and displaced therefrom either by equal or by unequal distances, and a pair of similar anodes in the form of a pair of interleaved helices, which the respective turns of the anodes and the control electrodes registering, or lying in the same right helicoidal path around the cathode, the electrons emitted from the cathode to the anodes may be considered as being divided into a plurality of parallel streams which may be deflected from each anode to the other in response to periodic variations in the electrastatic fleld produced by a periodic control voltage'applied between the con- With this form of tube strucfor use in the systems of the present invention are disclosed in my aforesaid copending application and described in detail hereinafter.

It is an object in my present invention to provide a frequency conversion system which in cludes an electron discharge device having the operating features described in the preceding paragraphs and which operates in an improved manner to produce the deslred modulation of one frequency by another with a minimum of distortion in the converted output. I

In accordance withmy invention, the abov object is attained by providing a'frequency con-- version system in which two diil'erent sources of alternating voltages having the same or diflerent frequencies are connected to the control means of the electron discharge control device of the general type described above, in such mannr that one of the voltages acts to control the total electron emission from the cathode tothe anodes and the other voltage acts to control the deflection of the electron streams alternately toward one and thenthe other of the .two anodes. With this arrangement, a voltage of one frequency may be modulated by that of another frequency and the voltage of either the sum or the difference voltage, so long as the variations in this voltage arevinsuflicient to produce. complete deflection of the electron streams from each of the two anodes *"Ttd'the other. In this. connection, it will be understood that the arrangement is such that the deflection control does not aflect the WM??? tron emission, since this would introduce distortion in the manner previously described.

The novel features which I believe to be charance with the invention disclosed in my afore-' mentioned copending application; Fig. 2 is a top view of the electron discharge device in Fig. 1;

.Fig. 3 is a fragmentary cross-sectional view of the electron discharge device shown in Fig. 1; Figs. 4-6, inclusive, are circuit diagrams illustrating different forms of my improved frequency-converter system; and Figs. 7-25, inclusive, illustrate further modifications of my improved freduencyconverter system resulting, in part, from certain modifications in the form of the electron discharge control device illustrated in Fig. 1.

Referring more particularly to Figs. 1, 2 and 3 of the drawings, there is illustrated one embodiment of my improved electron discharge device as disclosed in my previously mentioned copending application. This device is shown as comprising a plurality ofelements which may be supported froma press in ariy desired manner.

For purposes of clarity in describing the invention, the evacuated envelope within which the elements or the electron discharge device are )to be mo It will understood that any form of envelope ted has been omitted from the drawings.

may be employed which is evacuated to a degree iment of my improved electron discharge device illustrated, the control electrodes 3 and 4 are constructed in the form of interleaved helices which are coaxially disposed at equal distances from the cylindrical cathode 2 and are interposed between the cathode I and the pair of anodes 5 ,and 8. The anodes 5 and 6 are constructed in a similar manner to form interleaved helices having thesame pitch and the same direction of twist as the control electrodes, are coaxially disposed with respect to the cathode 2, andsurround the control electrodes 3 and I.

- Although any desired form of supporting means maybe employed, the type of means illustrated will provide the necessary rigidity of the structure to maintain the respective electrodes in their proper relative positions. a This means includes four metallic 8, 9, I0 and I I, for supporting the anodes 5 iand 6, and mica spacers l2,

.each provided with recesses along each ,edge

thereof which engage the turns of the anodes and the turns 0! the control electrodes to support the latter from the former. The metallic posts 8 and [may be spot-welded to theturns of the anode I at' points displaced 180 and are provided with cut-out portions 13' adjacent to the turns of the anode 6 which prevent any electrical conmotion between the two anodes within the tube.

- the two control electrodes.

gitudinally extending depressions l4 to accommodate the four supporting posts 8-, inclusive, and to permit the correct spacing of the shield with respect to the anodes without'a conductive connection therebetween.

The relative positions occupied by the respec- V tive electrodes are best illustrated in the fragmentary cross-sectional view shown in Fig. 3.

It will be seenthat the turns of one of the con.- trol electrodes and the turns of one of the anodes lie in the same right helicoid and register with each other. Thus, at the plane of cross sectioning the cross-sectioned surface of the electrode I is on a line perpendicular to the cathode 2 and passing through the anode 5. Similarly, and in the same plane the cross sectioned surface of the electrode 4 is on a line perpendicular to the cathode 2 and passing through the anode 8.

With the above-described arrangement of the elements, the two control electrodes function to separate the electrons .flowing toward the anodes into a plurality of streams. For example, each turn of each of the helical anodes and control electrodes may be considered to be a section of the electrodes of which it forms a part; the several sections, or turns, being connected together at their ends to form a continuous element. As.

thus considered, the helicoidal path extending substantiallyperpendicularly from the cathode and betweeneach adjacent pair of single turns of the two control electrodes may be described as constituting/a path for one'electron stream, and this path will be seen to be parallel to the path of the stream flowing in the helicoidal path perpendicular to the cathode and Lextendingbetween the, next adjacent pairs of single turns of the control electrodes. The rate of electron emission may be controlled by the combined effect of Thus, if the instan taneous potentials of the electrodes 3 and 4 with respect to the cathode 2 are equal and are varied equally and simultaneously, as by the application of the same instantaneous component of aperiodic voltage to both electrodes, the rate of emission of electrons will be varied accordingly, thereby to vary the magnitude of the current which can flow from either of the anodes 5 and 8 to the cathode 2. Also, the direction of the electron streams may be changed by varying the electrostatic fleld between the two electrodes 3 and 4,'

whereby a greater proportion of the emitted electrons will reach one anode than the other anode.

Thus considering the twolowermost turns of the control electrodes and anodes shown in Fig. 3, if the electrode 3 alternately'be made more negative with respect to the cathode 2 than the elec- .trode 4, so that the electrostatic fleld'between the I two electrodes is varied the electrons will alternat'ely be deflected toward one and then the otherof the anodes 5 and G; It will, therefore, be seen that, if an alternating voltage beimpressedbe- F tween the control electrodes 3' and 4, the electron streams will alternately be "deflected from each anode toward the other anode.

It will, of course, be understood that the divislon of the'streams of electrons between'the two. anodes will be influenced to a lesser degree by the relative potentials of the two anodes. For example, if the anode 5 be made more positive with respect "to-the cathode than the anode B, the

. operating features described above.

j electrons will be attracted with greater intensity toward the anode I, and vice versa. It will be seen that the electrons which pass between the .anodes 4 and i will, at least in part, be attracted back to these anodes, but some may reach the shield I, particularly if the potential of the shield is not sufllc'lently negative to overcome the initial velocity of the electrons. In order to minimize this tendency, the shield I may be biased toa potential slightly negative with respect to the cathode 2, thereby to repel the electrons toward the two anodes. However, if the initial velocity of the electrons be sufilciently low, the negative bias may be omitted and the shield I connected directly to the cathode 2. The shield I, which-encloses the anodes 5 and 6, is provided for a threefold purpose. In the first place, the shield prevents the electrons which pass between the anodes from accumulating on the inner surface of the tube'envelope and thereby prevents an undesired electrostatic charge from being built up on this surface. Secondly, the shield reduces the secondary emission of electrons from the momentarily less positive anode to the more positive anode; and; thirdly, the shield acts as an electrostatic shield to reduce the capactive couplings between the input circuits and the output circuits connected to the device. The shield is particularly effective in reducing the capacitive coupling between the two control electrodes jointly and the two anodes jointly. In order further to reduce secondary electron emission from one anode to the otherquency conversion'system which includes an elec'- tron discharge device having the structural and tom the input electrodes 3 and 4 of the electron In this sysdischarge device are connected to the terminals of the secondary winding ll of a transformer l8 having its primary winding l9 connected to a source (not shown) of alternating voltage having a frequency 11. The mid-point 20 of the s'e'condary'winding I1 is connected to the oath-- ode 2 through a by-pass condenser 2| and the secondary winding 22 of 'a transformer 23. The primary winding 24 of the transformer 23 is connected to a second source (not shown) of alternating voltage having a difierent frequency In. In order to bias the control electrodes 3 and 4 to the proper negative potential with respect to the cathode I, a source (not shown) of biasing potential may be connected between the terminals 25 and 2B, the negative side of this source being connected to the terminal '25. The anodes 5 and 6 of the electron discharge device are connected to the input terminals of a filter system,

of the control electrodes 3 and 4, thereby to vary a pair of series-connected by-pass condensers /the average potential thereof with respect to the cathode 2. In this manner, the rate of electron emission from the cathode! to the anodes 5 and 8 is controlled in accordance with the variations in the alternating voltage applied to the terminals of the primary winding 23. Also,

the control electrodes cause the emitted electrons to separate into a plurality of streams, as explained above, which, due to the positive potential of the anodes, travel toward the anodes. Simultaneously with the control of the electron emission, the electron streams thus formed are alternately deflected from each anode toward the other by the electrostatic field between the two control electrodes 3 and 4 produced by the alternating voltage impressed on the terminals 'of the primary winding IS. The anode currents,

' exist across the input terminals of the filter. The

filter 28 may be designed selectively to transmit to its output terminals a voltage having either of the t'woJrequency components noted.-

' vacuum tube 'cau'ses' coupling between the input and the output circuits connected thereto, which is often very undesirable and which is commonly made negligible by the interposition of ascreen grid between the control electrode and the anode. In the embodiment 01' my invention described above, this expedient is unnecessary, insofar as coupling between the input and output circuits isconcerned, for the reason that thesystem is almost completely self-neutralized. This is partly because each control electrode partly shields the other control 'electrode, and each anode partly shields the other anode; but is mainly because each anode has nearly equal capacitances (which have opposite effects) to the'two control electrodes, and each control electrode, similarly, has nearly equal capacitances to the two anodes.

' In the embodiment of my invention illustrated in Fig. 5, there is shown a system which may, by suitable adjustment of the circuit elements, alternatively be employed as a beat, frequency oscillator-modulator unit for a superheterodyne receiver, or asa zero beatfrequency oscillatordetector for use in a homodyne receiver. The circuit shown differs from that of.F'ig.'4 in that the second source of alternating voltage comprises a tunable resonant circuit which is maintained in continuous oscillation by impressing thereon an alternating voltage having the frequency of the resonant circuit and derived from the output .circuit of the oscillator-modulator The result is, in;

34 and 35.

The total electron emission from the cathode 2 to the anodes 5 and Ii is controlled by the voltage developed between the terminals of a resonant circuit 35 comprising a parallel-connected inductance 31 and variable condenser 38. This circuit is connected between each ofthe twoand is inductively coupled to the inductance 31.

It ,will be noted that the two branches of the output circuit are connected to the cathode 2 through the common connection which includes the winding 40 and a source of anode potential +3 shunted by a high-frequency by-pass condenser 42. It will further be noted that the control electrodes 3 and! may be biased to the proper negative potential with respect to the cathode. 2 by impressing between terminals 43 and 44 a source of unidirectional voltage of the proper value;

'\ If it be desired to operate themscillator-modulator system of Fig. 5-as the converter stage in a superheterodyne type of radio receiver, the pri-I' .mary winding 3|) may be connected to the output unit. Briefly described, the'system comprises a transformer .29 having a.primary winding. 33,

which is traversed by the modulated carrier current derived from a preceding portion of the 75 and 6, the primary winding 33 being shunted by circuit of the preceding radio-frequency amplifier stage, thereby to impress between thev control electrodes 3 and l a received modulated radio-frequency carrier voltage. produces deflection of the electron streams developed in the electron discharge device alter- This voltage 7 nately toward each of the two anodes 5 and '6, thereby to produce variations inthe division of V the anode current flowing therefrom toward the cathode 2- in accordance with the frequency of 'the incoming carrier. system being symmetrical with respect to the 4 The anode circuit of they cathode 2, the carrier frequency component oi?- this current balances out in the winding 33 so the no carrier-frequency component of voltage ap ars between the mid-point II and the cathode 2. With the system in operation, the sum of the two anode currents flows through winding Ill and impresses a voltage on the resonant circuit 33. This circuit may be adjusted, by means of the variable condenser 38, to a resonant frequency above or below the carrier frequency and difl'ering therefrom by any desired predetermined amount. By making the circuits which are energized from the winding 33 responsive to only the desired beat frequency, as modulated with the audio-frequency component of the received carrier and corresponding to the that, if this system be employed in the application noted, the adjustable element of the condenser 33 will be connected for unicontrol with the adjustable elements of the frequency-selecting circuits included in the preceding radiofrequency portion of the receiver.

By adjustment of condenser 33. in Fig. 5, to malee the circuit 36 resonant to the frequency ofthe signal carrier, the system may be caused v to operate as azero beat frequency oscillator of the general type employed in a homodyne detector.

Referring now to Fig. 6 of the drawings,there f5 is illustrated an oscillator-modulator unit which may be employed to modulate a radio-frequency voltage at an audio frequency and which is particularly useful for laboratorytesting purposes. The arrangement comprises a tunable radio-frequency resonant circuit 45, including a parallelconnected inductance 46 and a variable condenser 41, and a tunable audio-frequency resonant circuit 48 comprising an inductance 49 and a variable condenser 50. The resonant circuit 45 is connected between the control electrodes 3 and 4 and is inductively coupled to an inductance connected between the anodes 5 and B.

The circuit 48 is connected between each of these twocontrol electrodes and the cathode 2,

the application of voltage between the terminals 55 and '55, which terminals are shunted by a bypass condenser 51.

In the operation of the circuit shown in Fig. 6, energy is supplied to the two tunable frequency-determining circuits 45 and 48 through the respective inductive couplings between the windings 4B and 5| and the windings 49 and 52, thereby to maintain each of the two resonant circuits in continuous oscillation. With the two resonant circuits oscillating, an alternating voltage having a radio frequency determined by the resonant frequency of the circuit 46 is impressed between the two control electrodes .3 and 4, thereby to cause the above-described deflection of the electron streams alternately toward one and then the other of the two anodes ,5 and 6.

Simultaneously; an audio-frequency voltage is impressed between each of the two control electrodes 3 and 4 and the cathode 2 by the resonant circuit 48, thereby to control the total electron emission .to the anodes. Thus, the current flowing toward the cathode and through the winding 5| contains a radio-frequency component which is modulated at an audio frequency. Adjustment of the frequency of either the audioor radio-frequency components may be obtained by proper adjustment of the respective tuning elements 50 and 41.

While I have described my improved frequency-converter system as including an elec-' tron discharge control element having a pair of anodes symmetrically disposed with respect to the cathode 2, it may be found to be desirable to employ a control device in which the shield which encloses the other elements of the tube is used as one of the anodes. Such a tube structure is illustrated-in Fig. 7, wherein the sin-- roundin; metal cylinder 15 may be connected as an anode The structure of the tube shown in this figure is otherwise identical with that illustrated in Fig. 1. v r

'The use of the shield in place of one of the helical.anodes does not essentially modify the operation of the control tube, the deflecting action of the control electrodes 3 and 4 being such that the electron streams are deflected alternately toward the active surfaces of one and then the other of the two anodes 5' and II in scribed. It will, therefore, be apparent that this tube may be used in any of the previously described frequency conversion systems without substantial modification thereof. However, it may be desirable to employ a frequency-converter circuit arrangement as illustrated in Fig. 8, which is similar to that shown in Fig. 4; with the exception that only the anode 15 is directly connected intheoutput circuit, the. anode 5 being maintained at a fixed positive potential by the application of voltage thereto through the terminal 16. In this circuit the anode 5 functions as a screen grid between the control electrodes 3 and 4, and the single anode 15. As is usual in such circuits, the positive potential applied to the electrode 5 is maintained at a value less than that applied to the anode'l5. In this system, not only does the anode 5 serve as a screen grid greatly to decrease the inherent capacitance between the anode I5 and the control.

electrodes, but also the symmetrical arrangement of the control electrodes results in a large degree of self-neutralization, in the manner previously described.

In Fig. 9 there is illustrated a further modification of the electron discharge control device, wherein the helices are disposed in such a manner that the turns of the helical control electrodes are arranged in staggered relation with respect to each other, the turns of one of the electrodes being displaced from the cathode by a distance greater than the distance between the other electrode and the cathode. Thus, the control electrode 4 is shown as being a helix of larger diameter than the helix formed by the electrode 3 and concentrically positioned with respect to the cathode 2 about the control electrode 3. As thus arranged, the turns of electrode 4-are displaced a greater radial distance from the cathode 2 than the turns of the control electrode 3, and an unsymmetrical structure is produced in which the turns of the electrode 4 surround the turns of the electrode 3.

The dissymmetry of the tube structure does- ,not alter the fundamental electron deflecting action of the control electrodes, but it does make it desirable to employ an unsymmetrical input circuit connected between thesetwo electrodes. Such an unsymmetrical circuit arrangement is shown in Fig. 10, which is similar to the frequency converter circuit of Fig. 4 butdifiers therefrom in that the secondary winding of the transformer l8 isdivided into two sections 11 and. I8 having unequal numbers of turns.

The coil 11', having the greater number of turns, is connected to the controlelectrode 4 farthest removed'from the cathode 2 and the section 18, having the smaller number of turns, is connected to the control electrode 3 nearest the cathode 2. The operation of this circuit is essentially the same as that described in connection with the circuit of Fig. 4, the turn ratio of the windings I1 and 18 being adjusted so that fluctuations of the potentials applied to the control electrodes 3 and 4 by the transformer I8 do not produce any change in the total electron emission. Further, the turn ratios of the windings of the coupling means comprising the transformers l8 and 23 are so proportioned that the voltage impressed on the control electrodes to vary the total electron emission to the anodes doesflnot affect the deflection of the electron streams between tlietwo anodes. In this connection, it

will be understood that biasing potentials are applied to the control electrodes I and 4 through separate terminals, as by the terminals I9 and OIL For simplicity, only the control electrode 3 nearest the cathode is used for emission control, including in its circuit the secondary 22 of the transformer 23.

In the electron discharge device illustrated in Fig. 11, the anodeis omitted, the cylindrical electrode I5 operating as a second anode in the manner described in connection with Fig. 7; and the unsymmetrical arrangement of control electrodesis used as in Fig. 9. A tube having this structure may be employed in-an unsymmetrical frequency-converter circuit of the type illustrated in Fig. 12. In this circuit a source of voltage having a frequency i1 is' coupled by means of a transformer Bl to control the deflection of the electron streams between the .two anodes 5 and 15. The transformer 81 includes a pair of secondary winding sections 82 and 83 connected in series'between the control electrodes 3 and 4 by the ,coupling condenser 94. A source of voltage having a frequency jg, is simultaneously impressed on the electrodes 3 and 4, thereby to.

control the total electron emission to the anodes.

The connections between the source I: and the control electrodesinclude the transformer 85, comprising a primary winding 88 and two econdary windings 81 and 33. The output ircuit' connected between the anodes 5 and I5 and the cathode 2 includes the primary winding of a transformer 89 to which is connected at a pling transformers being adjusted to compensate for the dissyminetry produced by the unsymmetrical positioning of the control electrodes 3 and and the unsymmetrical arangement of the anodes 5 and 15. In both cases the relative numbers 'of turns of the transformers are such that the voltage of frequency i1 does not afiect the electron emission and the .voltage of frequency I: does not appear between the anodes 5 and 15.

In Fig. 13 there is illustrated a still further' modification, of the electron discharge control device, in which an additional pair of electrodes, comprisinga helical screen grid 9| and a helical suppressor grid 92, are included in the device in addition to the elements described in discussing Fig. 11.- A frequency-converter circuit including an electron discharge device having these two additional electrodes is illustrated in 131g. 14.

-In this circuit the suppressor grid 92 is shown as being connected within the tube to the cathode 2 and the. screen grid as being connected to l the positive terminal of a direct-current source +screen, so that the latter grid ismaintained u at a positive potential below that of the anodes 5 and 15. The fundamental-operation of'this circuit is essentially the same as that of each of the previously described frequency-converter circuits. Accordingly, a description thereof is deemedto be unnecessary.

In the electron discharge device illustraigd in Fig. 15, the metal cylinder 15 functions as a single anode and the helical electrode 93 functions as a screen grid. A helical suppressor grid 94 is provided which isinterposed between the electrode 93 and the anode 15. The circuit connections for the application of this electron discharge "device to a frequency-converter circuit i are illustrated in Fig. 16, which differs from the circuit shown in Fig. 14 only in. that a single anode is'employed, the screen grid is formed by the electrode 93, and, the electrode 94 is connected to the cathode 2'to form a suppresor grid. Y

In the structure of the electron discharge device'shown in Fig. 17, an additional control electrode 95 is provided between the cathode 2 and the interleaved helical control electrodes 3 and I. This electrode, when connected in a frequency-.

converter circuit, operates independently of the control electrodes 3 and 4 to control the electron emission from the cathode 2 to the anodes 5 and i the control electrodes 3 and 4 operating solely to deflect the electron streams alternately from one anode toward the other. Such a circuit, having embodied therein the tube of Fig. 17, is illustrated in Fig. 18, from which it will be seen that the only diflerences between the circuit of this figure and that of Fig. 4 reside in the connection of one terminal of the winding 22 to the aditional electrode 95 rather than to the electrodes 3 and 4 through the winding ll, and the connection of the otherterminal of the winding 22 to a separate source of bias at terminal 25'.

In each of the forms of the electron discharge device thus far described, the deflection control voltage and the emission control voltage have been impressed oncontrol electrodes distinct from the anodes. It will be understood, however, that one or both of these voltages may be impressed on the anodes by suitable circuit connections. For example, in Fig. 19 there is illustrated an electron discharge device which includes-the two anodes 5 and 5, the cathode 2, and a single electrode 95; for controlling the electron emission from the cathode 2 to the two anodes. This electron discharge device functions as a relay with respect to the electron emission control, in ..a manner analogous to the usual three-electrode vacuum tube. However, with respect to the electron deflection coritrol, it has no relay action, behaving in this respect in a manner analogous to a rectifier, the deflection control voltage being impressed between thetwo anodes.

A frequency conversion system, which includes a device having the construction shown in Fig. 19, is illustrated in Fig. 20, wherein the anodes 5 and 5 are connected through blocking condensers 91 and 98 to the secondary of a transformer 99, receiving through its primary winding terminals a current having a frequency h. The consequent alternate deflection of the electron streams from one anode to the other, produced by the voltage of frequency f1 impressed between the two anodes, is equivalent to the production of a current of frequency;& flowing between the anodes and through the secondary of transformer 99. A voltage having a frequency in may be impressed by a transformer Hill on the electrode 95, to vary the electron emission at a frequency is which, in effect, varies the resistance between the anodes 5 and 5 at this same frequency f2. It follows that component potential differences are built up between the anodes 5 and Shaving frequencies which are the sum and the difference of the frequency f1 and the frequency f2. By proper design of the filter llll connected to the anodes 5 and 6, a voltage'jiaving either the sum frequency or the' difference frequency of the frequencies f1 and'fz may developed across the output terminals of the filter. I

In the arrangement illustrated in Fig. 20, it is assumed that the difference frequency alone is lower than '11, so that it is effectively blocked from the input circuit by the condensers 91 and 98. Other well-known expedients may be used to separate the anode current from the input current, particularly if the output frequency is not considerably lower than {1, as, for example, if the sum frequency is desired. Thus, the input and output circuits may effectively be connected in series instead of inparallel.

Referring to Fig. 21 of the drawings, there is illustrated a system wherein the emission control voltage is impressed on the two anodes 5 and 6 and the deflection control voltage is impressed between the two control electrodes 3 and 4. The

circuit arrangement difiers from that of Fig. 4 only in that the emission control voltage of frequency f2 is impressed on the anodes instead of the control electrodes. To apply the voltage of frequency f2 on the two anodes, a transformer I02 is provided having a secondary winding I03 included in' the common connection between the.

two anodes 5and 6 and the cathode 2. In this system, the modulation is effected in the anode circuit in a manner analogous to the Heising system of modulation commonly used in radio transmitters.

In the circuit arrangement illustrated in Fig.

22, the two control electrodes 3 and 4 are omitted,

both of the control voltages being applied to the anodes 5 and 5. This circuit is similar to that shown in Fig. 20 but transformer I is omitted from the circuit, being replaced by a transformer I04 for impressing the voltage of frequency 3: be-

tween the anodes and I5 jointly and the cathode 2. The transformer I04 comprises a primary winding I05 traversed by the current of frequency )2 and a secondary winding I06 which is connected between the mid-point I01 of the secondary ries instead of in parallel.

winding of transformer 59 and the cathode 2 through the by-pass condenser I00. It will be understood that in this arrangement the two anodes may be symmetrically arranged, as indicated, or the outer shield may be used as ananode, one of the interleaved anodes 5 or 6 being omitted. As in Fig. 20, the deflection of the electron streams from one anode to the other is controlled by the voltage of frequency f1, impressed between the anodes by transformer 99. The emission, on the other hand, is controlled by the voltage of frequency is, impressed between the anodes jointly and the cathode by transformer I04. Like the system shown in Fig. 20, the input and output circuits are effectively connected in parallel. q

The arrangement shown inFig. 23 operates in a manner similar to that'of Fig. 22, but the input circuit and the output circuit are connected in se- This arrangement may sometimes be more convenient. A further difference between the two systems lies in the fact that the vacuum tube shown is unsymmetrical, one anode 5 having the form of a grid and the .other anode 15 having the form of a shield or.

plate external to the grid, being inthis respect similar to the anodes of Figs. 7 and 11, for example. The tube structure is, in fact, essentially that of an ordinary triode, but the circuit arrangement is quite different from that of conventional frequency conversion circuits wherein ordinary triodes are used. The input circuit corresponds closely to that of Fig. 12 and like reference characters are used t9 identify similar elements. The deflection control voltage of frequency fl is impressed between the anodes 5 and I5 by secondary windings 82 and 83 of transformer 8|;

these windings having such a turn ratio that the deflection control voltage does not affect the elec-' tron emission, as previously described. The emission control voltage of frequency I2 is impressed between the anodes 5 and I5 jointly and the cathode 2 by, secondary windings 8I-and 88 of transformer 85. denser 04' is provided to localize the current of frequency 11, which flows through the electrostatic capacity between electrodes 5 and I5, and' While not always necessary, contend to send a current of frequency f2 through the circuit including in series the three condensers shown. These refinements in the circuit arrangement are important only when the frequencies f1 and is are relatively high,

While the electron deflection control has been described as comprising a pair of control electrodes which, through their electrostatic action on the electron stream, produce the desired alternate deflection of the electron streams toward one and then the other of two anodes, it is pointed out in my previously referred to copending application that a similar *operation may be obtained by utilizing a varying magnetic field to produce the desired deflection of the electron streams. electron discharge device which comprises a cathode I09, about which are concentrically'disposed a pluralitypf axially extending filamentary grid sections 0 which are connected together within the tube to form a control electrode. Concentrically disposed with respect to the cathode I09 are a plurality of axially'extending filamentary anode sections I I I", alternate ones of which are connected together within the tube to form a pair of interleaved anodes. The number of grid sections is half the number of anode sections, each grid section registering with the passage between two adjacent anode sections. A shield II2 surrounds the assembly of the sections and is, in turn, enclosed within an-evacuated envelope II3 having a degree of vacuum suflicient to insure efficient substantially pure electron emission. In order to reduce eddy currents in the shield, a slit H2 is providedtherein which extends longitudinally along the shield. For the purpose of deflecting the electron streams between the two anodes,'a winding II t is placed around the envelope and includes connections for excitation by a suitable control current.

A frequency-converter circuit having included therein an electron dischargedevice of the con-.

struction illustrated in Fig. 24 is shown in Fig. 25. In this circuit, a source of alternating voltage having a frequency i1 is impressed on theterminals of the winding I and a second source of alternating voltage, having a frequency I2, is impressed, through the transformer IIB, on the emission control electrode II5, formed by the connected filamentary sections H0. The control electrode H5 is biased to the proper negative Thus, in Fig. 24 threis illustrated an and a source of anode voltage (not shown) electron emission control. -In this application the shunted by a lay-pass condenser I12.

vIn the operation of the circuit shown in Fig. 25, emission of electrons from-the cathode ,III to the two anodes is varied at a frequency I: by virtue of the voltage applied to the control electrode 5. Each electron stream emitted to thetwo anodes is deflected alternately toward one and then the other of adjacent anode sections by the alternating magnetic fleld produced withinthe discharge device by the winding Ill.

y for modulation.to provide the intermediate freis) will not appear in the output circuit.

quency in a superhetrodyne receiver, and for detection in a receiver. In all such uses, it is desired to combine a voltage of a single flxed fre-- quency with a signal voltage containing a band of frequencies. The advantage in minimizing dis-- tortion will, in general, be most fully realized ii the signal voltage is used for the deflection control and the single flxed frequency-for the emission control. However, this order of applying the voltages to the control means may be reversed.

In a transmitter, if a tube having a symmetrical arrangement of the anodes, such as that shown in Fig. 4, is used in a modulator system as illustrated, and the signal voltage is used for the electron deflection control- (I; being a component of the audio frequency) the carrier (of frequency Such a carrier suppression system may be used alone, or to supply the quadrature modulated component in a frequency modulation system of the type described in United States Patent No. 1,941,068, to Armstrong, granted December 26, 1933. If,

on the other hand, a tube having an unsymmetrical anode arrangementis used in a system such as that of Fig. 8, the signal voltage again being used for the electron deflection control, the system will operate to produce the usual amplitude modulation and the output will contain the carrier modulated by both sidebands of frequency.

r In 'a superhetrodyne receiver for amplitude modulated signals, if. the signal voltage is used for the electron deflection control (11 being a radio-frequency component of the signal) and thelooal oscillation is used for emission control (at the frequency 12), the signal voltage should be impressed between electrodes at a sufliciently 'low level to'give linear operation at all amplitudes of the modulated carrier. On the other hand, in a superhetrodyne receiver for frequency modulated signals, if the signal voltage again is, used for the electron deflection control, the signal'voltage may be impressed between electrodes at a high level so as to completely deflect the electron streams from one anode to the other, thus providing a limiting action useful in receiving such signals. Since this limiting action may not be fully effective over a wide range of signal intensities, it may be desirable to supplement this action by automatic amplification control applied 'to a preceding radio-frequency amplifier stage,

' to select from the signal he carrier voltage alone 76 (of frequency fa) which may then'bc used for the electron emission control voltage should be adiusted to be in phase with the carrier component of the electron deflection control voltage, in order to reproduce the original wave form of the audio- 5 frequency signal. When this phase relation exists; the two sidebands of an ordinary double sideband received signal will-be fully additive in their eflect, giving maximium response. Also, the combination of the electron emission control 10 voltage and the carrier component of" the electron deflection control voltage will give a maximum direct voltage (which corresponds to zero frequency). I This direct voltage may be used for control purposes in an automatic amplification 15 control system.

i In a homodyne detection system, which employs a local oscillation whose frequency is equal to the carrier frequency of-the signal, the complete signal voltage may be used for the electron 20 deflection control and a voltage from the local oscillation may then be used for the electron the preceding paragraph, thereby give the'result 25 ing operation therein set forth.

The arrangements described in the two preceding paragraphs give linear detection and so avoid the distortion: present in non-linear detectors, even of thesquare-law type. They are particu- 30 larly useful in the detection ofsignals in which only a single sideband is transmitted, since even the conventional self-rectifying linear detector inherently distorts such. signals, unless the carrier' component is exceedingly large relative to 35 the sideband components,.because the rectification occurs for the intervals during which the signal voltage has a certain direction and these intervals are not equal in a single sideband signal. This eflfect is absent in the systems herein 40 is arranged tobe normally in quadrature with the carrier component 'of the intermediate-frequency signal voltage, instead of in phase therewith. The combination of these voltages gives a direct voltage which is normally zero but whichdeparts from zero in one direction or the other if the 55 phase difference between the two voltages departs from quadrature. The two cases must be considered separately, according to whether the electron emission control voltage is derived from the sharply selected carrier or from a local homo 6o dyne oscillator. In the former 0389p the phase difference just mentioned changes rapidly as the intermediate frequency departs from the resonant I frequency of the sharply tuned circuit; and the direct voltage obtained is. available for controlling the frequency of the superhetrodyne oscillator in sucha manner as to bring the intermediate frequency substantially into coincidence with they resonant frequency. In the latter case, the di rect voltage obtained is available for controlling the phase of the heterodyne oscillator in such a manner as to bring the phase difference men-- tioned substantially. into quadrature. If desired, this phase correction may be used to supplement the frequency correction just described.

, Although in certain of the variousembodiments of the improved electron discharge device described herein, the control electrodes and the anodes are described as being helical in form, it will be understood that they may be made in any of various suitable forms, several of which are described in my above-mentioned copending application. In this connection, it will be understood that the term section appearing in this specification and in the appended claims is used in its broad sense to denote one of the elemental components of any form of electrode. For example, in the helical form described, even though the electrodes are actually continuous helices and the electron stream is actually continuous, to aid in the analysis of the operation of the tube, the electrodes may be considered to comprise a plurality of elemental turns or sections and the electron stream may be considered to be made up of a plurality of substantially annular streams bonded by the adjacent sections of the two electrodes. In such a structure the term scction", thus, refers to any single elemental component or turn. In the planar form of electrode, the term refersto any single conductor electrically connected to the common connection between the several conductors.

It will further be understood that the term interleaved, appearing herein, is used broadly to denote the relation of the two electrodes by which corresponding elemental sections, or surfaces, of each electrode directly exposed to the cathode alternate with corresponding sections, or surfaces,of the other, whether or not such sections or surfaces are actually at equal dis tances from the cathode. For example, in the form of 'the device wherein the corresponding turns or sections of the two control electrodes have different diameters and do not register with each other, the electrodes maybe regarded as interleaved. Again, in the embodiment wherein only onehelical anode is provided and the cylindrical electrode is connected to function as the second anode, the helical inner surface of the cylindrical electrode lying between the turns of the helical electrode and directly exposed to the cathode may be regarded as an anode interleaved with the helical. anode, since the electron streams are alternately deflected between the sections of this surface and the turns of the helical anode.

While I have described what I at present consider to be the preferredrembodiments of my invention, it will, of course, be understood that I do not wish to be limited thereto, since many modifications in structure of the electron discharge device disclosed and of the circuits employed may be made, and I contemplate by the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What is claimed is:

1. A frequency conversion system comprising, an electron discharge device including 'a pair of anodes, each of said anodes comprising a plurality of sections, the sections of one anode being disposed adjacent to the sections of the other anode, a control electrode, and a cathode for emitting electrons to said anodes, means including said control electrode for separating said electrons into a pluralityof streams, each of said streams dividing between a section of. one anode and an adjacent section of the other anode, an

output circuit coupled to said anodes, two altering a frequency difl'erent from the frequency of the other voltage, means for alternately deflecting each of said streams toward one and then the other of its respective adjacent anode sections at the frequency of one of said voltages, without affecting the total electron emission to said anodes, to vary the division of current between said anodes thereby to produce current variations in said output circuit at said frequency, and means including said control electrode for varying the total electron emission to said anodes at the frequency of the other of said voltages to modulate said current variations in said output circuit at said other frequency,

2. A frequency conversion system comprising, an electron discharge device including a pair of anodes, each of said anodes comprising a pluf rality of sections, the sections of one anode being disposed adjacent to the sections of the other anode, a first control electrode, a pair of additional electrodes, and a cathode for emitting electrons to said anodes, means including said additional electrodes for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit coupled to said anodes, a first source of alternating voltage coupled between said additional electrodes for alternately deflecting each of said streams toward one and then the other of its respective adjacent anode sections at'the frequency of said first source to vary the division of current between said anodes thereby to produce current variations in said output circuit at said frequency, and a second source of alternating voltage coupled to said control electrode for varying the total electron emission to said anodes at the frequency oi said second source thereby to modulate said current variations in said output circuit at said last named frequency.

3. A frequency conversion system comprising, an electron discharge device including a pair of anodes, each of said anodes comprising a plurality of sections, the sections of one anode being disposed adjacent to the sections of the other anode, a first control electrode, a pair of additional electrodes, and a cathode for emitting electrons to said anodes, means including said additional electrodes for separating ,said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an

from said first source, said second source being coupled to said control electrode to vary the total electron emission to said anodes at thefrequency of said second source thereby to modulate said current variations at the frequency of said second source.

4. A frequency conversion system comprising,

an electron discharge device including a pair of anodes, each of said anodes comprising a plurality of sections, the sections of one anode being disposed adjacent to the sections of the other anode, a first control electrode, a pair of additional electrodes, and a cathode for emitting electrons to said anodes, means including said additional electrodes for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit coupled to said anodes, a first source of alternating voltage coupled between said additional electrodes for alternately deflecting each of said streams toward one and then theother of frequency, and means for deriving from said out-- put circuit a voltage having only. one of the frequency components of modulation therein.

5. In combination, an electron discharge device including apair of anodes, each of said' anodes comprising a plurality of'sections, the sections of one anode being disposed adjacent to the sections of the other anode, a cathode for emitting electrons to said anodes, and a pair of control electrodes unsymmetrically disposed with respect to said cathode, means including said control electrodes for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit coupled to said anodes, a first source of alternating voltage, coupling means for impressing said voltage/ between said control electrodes alternately to deflect each of said streams toward one and then the other of its respective adjacent anode sections at the frequency of said first source thereby to vary the division of current between said anodes and to produce current variations'in said output circuit at said frequency, a second source of alternating voltage, and coupling means for impressing said second voltage on said control electrodes to vary the total electron emission, to said anodes at the frequency of said second voltage thereby to modulate said current variations at said last named frequency, said coupling means being proportioned so that the voltage impressed on the control electrodes to vary the total electron emission to the anodes does not affect the deflection of the electron streams between the sections of the two anodes.

6. A frequency conversion system comprising;

an electron discharge device including a cathode,

acontrol electrode and a pair of anodes, each of said anodes comprising a plurality of sections, the sectionsof one anode being disposed adjacent to the sections of the other anode, an output circuit including connections to each. of said anodes and a common connection to said cathode, t'wo alternating voltage sources, means for impressing one of said. voltages between said control electrode and said cathode thereby to produce variations in thecurrent in said output circuit at the frequency of said impressed voltage, and means for impressing the other of said' '7. A frequency conversion system comprising,

.an electron discharge device including a pair of anodes, each of s id anodes comprising a plurality of sections, the sections of one anode being disposed adjacent to the sections of the otherv anode, a cathode for emitting electrons to said anodes, and a control electrode, means including said control electrode for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit coupled to said anodes, two alternating voltage-sources, means for impressing one of'said voltages between said anodes alternately to deflect each of said streams toward one and then the other of its respective adjacent anode sections at the frequency of said impressed voltage thereby to vary the division of current between said anodes and to produce current variations in said output circuit at said frequency, and means for impressing the other of said voltages on said control electrode to vary the total electron emission to said anodes at the frequency of the other voltage to modulate said current variations at said last named frequency.

' 8. In combination, an electron discharge device including a pair of anodes, each of said anodescomprising a plurality of sections, the sections of one anode being disposed adjacent the sections of the other anode, a cathode for emitting electrons to said anodes, means for sep aratingsaid electrons into a plurality of streams, each of .said streams dividing between a section of one anode and an adjacent section of the other anode, two alternating voltage sources, means for alternately deflecting each of said streams towards one and then the other of its respective adjacent anode sections at the frequency of one of said voltages to produce variations in the division of current between said anodes, means for varying the total electron current to said anodes at the frequency of the other of said voltages, whereby the individual anode currents vary at heterodyne frequencies, and means comprising an output circuit connected directly between said anodes for deriving heterodyne-frequency potentials from the system.

9. In combination, an electron discharge device including a pair of anodes, each of said anodes comprising a plurality of sections, the sections of one anode being disposed adjacent the sections of the other anode, a cathode for emitting'electrons to said anodes, means for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, two alternating voltage sources, means for alternately deflecting each of said streams to- -wards.one and then the other of its respective adjacent anode sections at the frequency of one of said voltages, without affecting the electron ,emission to said anodes, to produce variations in the division of current between said anodes, means for varying the total electron current to said anodes at the frequency of the other of said voltages, whereby the individual anode currents vary at heterodyne frequencies, and means comprising an output circuitconnected directly between said anodes for deriving heterodyne-frequency potentials from the system.

10. In combination, an electron discharge dearating said electrons into a plurality of streams,

each of said streams dividing between auction of one anode and an adjacent section of the other anode, two alternating voltage sources, one of said voltages having a frequency different from the frequency of the other of said voltages, means for alternately deflecting each of said .streams towards one and then the other of its respective adjacent anode sections at the frequency of one of said voltages to produce variations in the division of current between said anodes, means for varying the total electron current to said anodes I at the frequency of the other of said voltages, whereby the individual anode currents vary at heterodyne frequencies, and means comprising an output circuit connected directly between said I anodes for deriving heterodyne-frequency potentials from the system. 7

11. Incombination, an electron discharge de- I vice including 'a pair of anodes, each of said anodes comprising a plurality of sections, the sections of One anode being disposed adjacent the sections of the other anode; a cathode for emitting electrons to said anodes, means for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode-and an adjacent section of the other anode, two alternating voltage sources, one of said voltages having a frequency different from the frequency of the other of said voltages, means for alternately deflecting each of said streams towards one and then the other of its respective adjacent anode sections at the frequency of one of said voltages, without affecting the electron current to said anodes, to, produce variations in the division of current between said anodes, means for varying the total electron'current to said anodes at the frequency of the other of said voltages, whereby the individual anode currents vary at heterodyne frequencies, and means comprising an output circuit connected directly between said anodes for deriving a voltage having only one of the heterodyne-frequency components therein.

12. In combination, an electron discharge device including a pair of anodes, each of said anodes comprising a plurality of sections, the sections of one anode being disposed adjacent the sections of the other anode, a cathode for emitting electrons to said anodes, means for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit connected between said anodes, two alternating voltagesources, one of said sources comprising an adjustable resonant circuit, means for exciting said resonant circuit by an alternating voltage derived from said output circuit-means for alternately deflecting each of said electron streams towards one and then the other of its respective adjacent anode sections at the frequency of the other of said voltages to vary the division of current between said anodes at said frequency, and means for varying the total electron current to said anodes at the natural frequency of said resonant circuit whereby the individual anode currents vary at heterodyne frequencies, said output circuit including means for deriving heterodyne-frequency potentials from the system.

13. In combination, an electron discharge device including a pair of anodes, eachof said anodes comprising a plurality of sections, the sections of one anode being disposed adjacent to the sections of the other anode, a cathode for emitting electrons to said anodes, means for separating said electrons into a plurality of I streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit connected between said anodes, an alternating voltage source, an adjustable resonant circuit, a feedback path coupled between said output circuit and said resonant circuit, means for alternately deflecting each ofsaid electron streams towards one and then the other of its respective adjacent anode sections at the frequency of said source to vary the division of current between said anodes at said frequency, and means'fOr varying the total electron current to said anodes at the .for emitting electrons to said anodes, means for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit connected between said anodes, two alternating voltage sources, means for alternately deflecting each of said streams towards one and then the other of its respective adjacent anode sections at the frequency of one of said voltages to vary the division of current between said anodes, and means for varying the total electron current to said anodes at the frequency of the other of said voltages, whereb the'individual anode currents vary at heterodyne frequencies, said output circuit including means for deriving heterodynefrequency voltages from the system.-

15. A frequency conversion system comprising an electron discharge device including a pair of anodes, each of said anodes including a plurality of sections alternating with and closely spaced with respect to each other, a cathode for emitting electrons to said anodes, means for separating said electrons into a plurality of streams,

each of said streams dividing between a section division of current between said anodes, and

means for varying the total electron current to said anodes at the frequency of the other of said voltages, whereby the individual anode currents vary at heterodyne frequencies, saidoutput circuit including means for deriving a voltage having only one of the heterodyne-frequency components therein.

16. A frequency conversion system comprising an electron discharge device including a pair of interleaved anodes, each of said anodes including a plurality of sections alternating with and closely spaced with respect to each other, a cathode for emitting electrons to said anodes, means for separating said electrons into a plurality of streams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit coupled directly between said anodes, two. alternating voltage sources, means for alternately deflecting each 01 said streams towards one and then the other of its respective adjacent anode sections at the frequency of one of said voltages, and means for varying the total electron current to said anodes at the frequency of the other of said voltages, whereby the individualsanode currents vary at heterodyne frequencies, said output circuit including means for deriving heterodynefrequency voltages from the system.

17. A frequency conversion system comprising an electron discharge device including a pair of interleaved anodes, each of said anodes including a plurality of sections alternatingwith and closely spaced with respect to each other, a cathode for emitting electrons to said anodes, meansfor separating said 'electronsinto a pinrality oistreams, each of said streams dividing between a section of one anode and an adjacent section of the other anode, an output circuit connected directly between said anodes, two alternating voltage sources, means for alternately deflecting each of said streams towards one and then the other of its respective adjacent anode sections at the frequency of one of said voltages to vary the division of current between said anodes, and means for varying the total electron current to said anodes atrthe frequency of the other of said voltages, whereby the individual anode currents vary at heterodyne frequencies, said output circuit including means for deriving a voltage having only one of the heterodynefrequency components therein.

LOUIS A, HAZELTINE. 

